Pyridyl-pyrazolidine 3-ones



United States Patent 3,178,441 PYRlDYL-PYRAZOLIDINE 3-0NES Geoffrey Ernest Ficken, Ilford, Essex, England, assignor to Ilford Limited, Ilford, Essex, England, a British company No Drawing. Filed Dec. 10, 1962, Ser. No. 243,598 Claims priority, application Great Britain, Dec. 19, 1961, 45,466/ 61 6 Claims. (Cl. 260-295) This invention relates to a new class of photographic developing substance and to the use thereof in the development of silver halide photographic emulsion layers.

In specification No. 542,502 there is described a process for the development of reducible silver salt images in photographic materials which comprises treating the materials with an aqueous solution containing a 3- pyrazolidone of the general Formula I:

where R R and R are the same or different and are hydrogen atoms or hydrocarbon groups.

Of the foregoing compounds, the compound l-phenyl- 3-pyrazolidone has received widespread commercial use, for which purpose it is customarily employed in association with another photographic developing substance with which it exhibits a superadditive effect. Thus it may be used in association with hydroquinone, hydroxyphenyl glycine, gentisic acid, ascorbic acid, reductone and other substances.

Subsequently it was shown that similar, though not necessarily identical, developing characteristics were possessed by corresponding compounds in which the one or both of the hydrogen atoms shown in the 4 and 5 positions of the compounds of the foregoing formula were replaced by substituent groups such as hydrocarbon residues. p

A difficulty which has been experienced with the compound 1-phenyl -3-pyrazolidone lies in its limited solubility in alkaline media.

. It has now been found that 3-pyrazolidone derivatives as defined below are extremely useful developing agents latl high vpI-l values and have a substantially greater solu- 1 ity.

According to a first feature of the present invention there are provided 3-pyrazolidone derivatives of the general Formula II:

Rt-OH NH Rn (II) wherein R is a heterocyclic substituent and R is an aryl, substituted aryl or heterocyclic group.

In the foregoing formula R may be, for example, furyl, thienyl, pyrryl, indolyl, pyridyl, thiazolyl, piperidyl, morpholinyl, pyrrolidinyl or benziminazolyl. R may be, for example, a phenyl group or an alkyl-, alkoxy-, halogenor other substituted phenyl group, or any of the heterocycles referred to above.

These compounds are not effective photographic developing agents for silver halide emulsions at pH values below about 9.5. At pH values above that level they show a very strong superadditive effect with such auxiliary developing substances as hydroquinone, and they have the especial merit of having a high solubility in highly alkaline solutions.

3,178,441 Patented Apr. 13, 1965 ice Processes for the production of the S-pyrazolidone types of developer compound are described, for example, in specifications Nos. 542,502, 703,669 and 728,368. Of the various known methods, those of specifications Nos. 703,669 and 728,368 can most readily be adapted to the production of compounds according to the present invention, and according to further features of the present invention, therefore, compounds of general Formula II are prepared by:

(a) Reacting a hydrazine of the general Formula III:

R NH.NH (III) with an ester of the general Formula IV:

R -CH=CH--COOR (IV) where R is a hydrocarbon group and the other symbols have the meanings hereinbefore assigned.

(b) Reacting a hydrazine of the general Formula III with an amide of the general Formula V:

(c) Reacting a hydrazine of the general Formula III with a compound of the general Formula VI:

R CH-: CHCN (VI) and subjecting the resulting 3-imino pyrazolidone to hydrolysis.

(d) For the production of compounds of general Formula II where R is a benziminazole residue reacting a compound of the general Formula VII:

R: with an orthophenylene diamine.

The new developing substances of the present inven-' tion may be used in the same manner as 1-phenyl-3- pyrazolidone, but at pH values above 9.5, in association with hydroquinone, hydroxyphenyl glycine, or any other known developing agent with which the new compounds exert a superadditive effect.

The following examples will serve to illustrate the invention:

(VII) EXAMPLE 1 1-phenyl-5-2'-pyridylpyraz0lidin-3-0ne l-phenyl-5-3-pyridylpyraz0lidin-3-one This was prepared by the method of Example 1, but using ethyl 3-3'-pyridylacrylate. The pyrazolidin-El-one formed colourless plates, M. Pt. 127-128", by crystallisation from ethyl acetate.

EXAMPLE 3 l-phenyl-5-4'-pyridylpyrazolidind-one The method of Example 1 was used with ethyl 3-4- pyridylacrylate. The pyrazolidin-3-one formed colourless plates, M. Pt. 161-162, by crystallisation from a mixture of ethanol and water.

EXAMPLE 4 1 -p-chlr0pIze1zyI-5 -3 '-pyridylpyrazolidin-3-0ne EXAMPLE 5 1,5-bis-4-pyridylpyraz0lidin-3-0ne A solution of sodium (3.2 g.) in ethanol 100 ml.) was refluxed for 16 hours with 4-hydrazinopyridine (11.5 g.) and ethyl 3-4-pyridylacrylate (18.7 g.). The residue obtained after evaporation of the solvent under reduced pressure was refluxed with concentrated hydrochloric acid (80 ml.) for 2 /2 hours. The cooled solution was filtered, and the filtrate treated with crystalline sodium acetate (100 g.). The solid which separated was collected, washed thoroughly with cold water, and purified by dissolving in dilute hydrochloric acid and reprecipitating with aqueous ammonia. The pyrazolidin-B-one formed off-white crystals, M. Pt. 329-331 (decomp.).

EXAMPLE 6 5-2'-furyl-1-phenylpyrazolidin-S-one A solution of sodium (2.0 g.) in ethanol (70 ml.) was refluxed for 25 hours with henylhydrazine (6.5 ml.) and 3-2'-furylacrylamide (8.95 g.). The solvent was removed under reduced pressure, and a solution of the residue in water (70 ml.) was acidified with acetic acid. The tar which separated initially slowly gave a solid, which was collected and crystallised from a mixture of benzene and light petroleum. The pyrazolidin-3-one formed colourless plates, M. Pt. 88-89".

EXAMPLE 7 1-phenyl-5-2'-thienylpyraz0lidin-3-0ne Phenylhydrazine (16 ml.) and 3-2'-thienylacrylonitrile (22 g.) were refluxed for 16 hours in ethanol (65 ml.) containing sodium (0.65 g.), and the solid which separated on cooling was filtered off and dried. This crude 3- imino-1-phenyl-5-2'-thienylpyrazolidine, M. Pt. 174-179, was refluxed for 16 hours with a mixture of concentrated hydrochloric acid (5.5 ml.) and water (50 ml.), and the resulting aqueous solution was decanted from the sticky solid which had separated. This solid was dissolved by warming in 2 N sodium carbonate solution (50 ml.) and the solution was filtered hot (charcoal). Acidification of the filtrate caused the separation of a solid, which was crystallised from aqueous ethanol to yield the pyrazo- 1idin-3-or1e as cream-coloured needles, M. Pt. 148-151".

EXAMPLE 8 5 -2-bcnzim inazolyl-I -phenyl pyraz0lidin-3-0r1e A mixture of 3-oxo-1-phenylpyrazolidine-S-carboxylic acid (5.0 g.), o-phenylene-diamine (2.62 g.), and 4 N hydrochloric acid (25 ml.) was refluxed for 2 hours.

The solution was filtered hot (charcoal), and the cooled filtrate was neutralised with aqueous ammonia. The

solid which separated was collected and crystallised from methanol to yield the pyraZolidin-3-one as colourless plates, M. Pt. 271-273" (decomp.).

EXAMPLE 9 5-2-benzimidaz0lyl-1-p-tolylpyraz0lidin-3-0ne hydrochloride A mixture of 3-oxo-1-p-tolylpyrazolidine-S-carboxylic acid (3.32 g.), o-phenylene diamine (1.63 g.), and 4 N hydrochloric acid (16 ml.) was refluxed for 2 hours. The crystalline solid which separated was collected after cooling the mixture, and was crystallised from dilute hydrochloric acid, to give the pyrazolidin-3-one hydrochloride a cream-coloured prisms, M. Pt. 265-267 (decomp).

EXAMPLE 10 The following is a suitable developer composition according to the invention:

G. Sodium sulphite (anhydrous) 24 Potassium sulphite (anhydrous) 20 Potassium canbonate (anhydrous) 10 Hydroquinone 1 1 1-phenyl-5-2-pyridylpyrazolidin-3-one 0.275 Sodium hydroxide 3.6 Potassium bromide 4 S-mercaptol-phenyltetrazole 0.01

Water to make 1 litre.

I claim: 1. A pyrazo1idin-3-one compound of the formula:

1I2C-C=O Rl- H 1111-1 where R is selected from the group consisting of 2- pyridyl, 3-pyridyl and 4-pyridyl and R is selected from the class consisting of phenyl, halophen'yl and tolyl.

1-p1enyl-5-2-pyridylpyrazolidin-3-one. 1-phenyl-5-3'-pyridylpyraZolidin-3-one.

. l-phenyl- 5-4'-pyridylpyrazolidin-3-one.

1-p-chlorophenyl-5-3-pyridylpyrazolidin-3-one.

. 1,5-bis-4-pyridylpyrazolidin-3-one.

P MA References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Bernthsen et al.: Organic Chemistry, 1931 Ed., pp. 567-571 (Blackie).

Sidgwick: Organic Chemistry of Nitrogen, 1937 Ed., pp. 521-7.

WALTER A. MODANCE, Primary Examiner. D. MCCUTCHEN, JOHN RANDOLPH, Examiners. 

1. A PYRAZOLIDIN-3-ONE COMPOUND OF THE FORMULA: 